Detent



June 14, 1960 J. BOWMAN 2,940,333

DETENT Filed May 15, 1958 INVENTOR.

20 J0 E BOWMAN ATTORNEY DETENT 3 Claims. (Cl. 74-527) This inventionrelates generally to detents, and more specifically to an improveddetent for an axially movable shaft.

Although the principles of the present invention may be included invarious devices, a particularly useful application is made in a sequencetimer wherein the selector knob is connected to a shaft which not onlyis axially movable, but which is rotatable.

The present invention contemplates the utilization of a spring and aspring retainer with the shaft and the housing which supports the shaftto obtain a detent structure wherein the shaft is securely held ineither or two selectable axial positions. In the instant embodiment, aconsiderable axial detent force is desired so that normal axial forcesacting on the shaft will not cause an axial shift thereof.

Accordingly, it is an object of the present invention to provide adetent which is capable of withstanding a considerable force before itallows a shaft to shift axially.

Another object of the present invention is to provide an improvedsimplified detent.

Yet another object of the present invention is to provide a detentwherein the spring is not easily disassociated and wherein it isimpossible for the spring to creep out of its normal operative position.

Many other advantages, features and additional objects of the presentinvention will become manifest to those versed in the art upon makingreference to the detailed description and the accompanying sheet ofdrawings in which a preferred structural embodiment incorporating theprinciples of the present invention is shown by way of illustrativeexample.

On the drawing:

Figure 1 is an elevational View of a timer assembly equipped with adetent provided in accordance with the principles of the presentinvention;

Figure 2 is a fragmentary view, partially broken away, taken along linelI-II of Figure 1;

Figure 3 shows the structure of Figure 2 with the shaft inwardlyshifted; and

Figure 4 is an exploded view of the various elements in the detentassembly.

As shown on the drawings:

The principles of this invention are particularly useful when embodiedin an electrical timer assembly such as illustrated in Figure 1,generally indicated by the numeral 10. The timer assembly includes apair of complementary housings 11, 12 to which is secured a motor 13which drives a series of cam actuated switches within the housing 11,12. Terminals 14 are provided to make electrical connections asrequired.

Within the housing 11, 12, there is disposed a rotatable face cam 15 towhich there is secured a shaft 16 by means of which the cam 15 may bemanually rotated. While the cam 15 and the shaft 16 are corotatable, theshaft 16 may be shifted axially with respect to the cam 15. The shaft 16is provided ,at its inner end with a fixed ted States Patent "ice ring17, one side of which is engageable with the movable blade 18 of anelectrical switch. When the shaft 16 is disposed upwardly as shown inFigure 2, the ring 17 raises the blade 18 so that the contacts 19 aredisengaged. Typically, these contacts represent the master switch of theappliance which the timer 10 controls. When the shaft 16 is disposed inan inward or downward direction such as shown in Figure 3, the naturalresilience of the blade 18 coupled with the inward movement of the ring17 permits the contacts to engage.

It can be seen that the weight of the shaft 16 and of any knob securedthereto will tend to cause the shaft 16 to shift in one direction or theother depending upon the attitude in which the timer 10 is mounted.Further, vibration of the apparatus to which the timer 10 is mountedalso has a tendency to intermittently open or close the contacts 19.

Accordingly, the detent assembly shown in Figure 4 has been provided forthis structure so that the shaft 16 will be positively held in oneposition or the other wherein the contacts are positively maintainedopen or positively maintained closed.

The housing 11 is provided with an upstanding portion 20 which has apair of generally parallel shoulders 21 and 22 disposed on oppositesides of the shaft 16 in generally parallel relation to the axisthereof. Thus also, the housing 11 has an aperture (not shown) throughwhich the shaft 16 extends and in which it may rotate.

As best seen in Figure 4, the upstanding portion 20 of the housing 11 isprovided with a pair of spaced slots 23, 24 extending transversely tothe shoulders 21, 22 and disposed on opposite sides of the shaft 16.Thus the sides of the slots 23 and 24 are each defined by one side ofthe housing and a shoulder spaced therefrom. Intermediate the slots 23,24 and surrounding the shaft 16 there is a slightly raised portion 25.It is to be understood that the shaft 16 shown in Figure 4 is partiallywithdrawn from the housing to illustrate the structure.

The housing may further be provided with a pair of apertures 26, 26which may be used in the mounting of the timerrto an appliance.

The shaft 16 has a pair of recesses 27, 27 each one of which is definedby a square shoulder 28 and an intermediate barrier portion 29 havingoppositely directed cam surfaces. Thus the cam surfaces on the barrier29 may be termed axially oppositely directed camshoulders.

Within one of the recesses or grooves 27, at least one of the resilientfingers 30 of the spring 31 is tangentially received. The spring 31 hasa natural configuration which extends about a portion of the upstandingpart 20 of the housing 11, and wherein the fingers 3% have a natural orfree position with a spacing therebetween which is less than thediameter of the shaft 16.

The retaining clip 32 is received in the housing slots 23, 24 with thespring 31 disposed between the clip 32 and the raised housing portion25. With this arrangement, shifting of the spring 31 in the direction ofthe axis of the shaft 16 is thereby precluded. The retaining clip .32has an angularly directed flange portion 33 and a pair of deformablefinger portions 34, 34. The angularly directed portion becomes disposedagainst one of the shoulders 21, 22, while the portions 34, 34 afterassembly, are angularly deformed against the other of such housingshoulders. The portions 33, 34 thus function to prevent removal of theclip 32 from the housing. The clip 32 also is slotted as at 35 toprovide a clearance for the shaft 16.

When the shaft 16 is in its innermost position, and an outwardlydirected force is applied thereto, the outer cam surface of the barrier29 acts to cause the fingers 36 of the spring 31 to yield radially ofthe shaft. The clip 32 acting on the upper or outer surface of thespring 31, and backed up by the outer shoulder defining the slots 23,24, serves to prevent movement of the spring 31 in the-direction ofshaft-movement;** r p When the fingers 30, c1ear-the-outer diameter ofthe barrier 29, they reengage in the othergroove or recess 27 to holdthe shaft in a second axial position. 7

It can be seen that when an oppositeforce is applied to an outwardlydisposed shaft, the oppositecam surface 'of the barrier 29' acts tospread the fingers30 which are backed up by the raised housing portion25;-until-the outer diameter of such barrier is again' cleared By thisstructure, the shaft 16 is positivelyheld'rin either of two axialpositions, which can easily 'be detected by the operator who applies anaxial force to theshaft,

and 'therefore the-contacts 19 are positively'held' in 'the desiredposition, Itis apparent that this:structur e permits free rotation ofthe shaft 16 incither of its axial positions. s r r 1 Although variousminor modifications might be -suggested by those versed in the art,itshould be understood that I Wish to embody within the scope of thepatent warranted hereon all such embodiments asreasonably and properlycome within the scope of my contribution to'the art. I

I claim as my invention: 1; A detent assembly comprising in combination:a housing having a shaft aperture extending through a side thereof, saidhousing having a pair of generally parallel shoulders directed away fromeach other and disposed on opposite sides of said aperture, and a pairof spaced slots extending transversely to said shoulders; a shaftreciprocably disposed in-said aperture and having at leastfone axiallydirected 'cam shoulder defining a circumferentially directed recess; aspring having at least one-resilient finger tangentially receivable insaid recess,

shoulders directed away from each other and lying in planes generallyparallel to the axis of said aperture, said shoulders being disposed onopposite sides of said aperture, said housing having means remote fromsaid shoulders defining a pair of spaced open-ended slots extendingtransversely to said shoulders, and disposed therebetween; a shaftreciprocably disposed in said aperture and having a pair ofcircumferentially directed grooves each defined by an axially oppositelydirected cam shoulder and another shoulder; a spring having at least oneresilient finger tangentially receivable in one of said grooves, saidfinger being yieldable radially of said shaft in response to axialmovement thereofgand a retainin'g'clipl received in said housing slotsfor retaining said spring, said clip having portions remote from saidslots, at least one of which portions is bendable, said clip portionsreceiving said housing shoulders therebetween and embracingly engagingsaid housing shoulders for retaining saidclip.

3. A detent assembly comprising inlcombination; a housing having a shaftaperture extending through a side thereof; said housing having a pair ofgenerally parallel shoulders directed away'from each other, and disposedon opposite sides of said, aperture; a pair of posts on said housingeach intermediate and adjacent to both of said finger being yieldableradially ofsaid shaft in re- 7 spouse to axial movement thereof; and aretaining clip received in said housing slots for retaining said spring,said, clip having portions extending generally parallel to said shaftbeyond said slots, at least one of which portions is bendable, said clipportions receiving said housing shoulders therebetwe'en andembracinglyengaging said housing shoulders for retaining said clip.

2. A detent assembly comprising in combination: a

housing having a shaft aperture extending through a side thereof, saidhousing having a pair of generally parallel said housing shoulders anddisposed on opposite sides of said aperture, said posts each having aslot extending transversely to said shoulders; a shaft reciprocablydisposed in said aperture and having atleast one axially directed camshoulder defininga cireumferentiallytdirected recess; a generally'U-shaped spring having its closed end extending over about one of saidhousing posts, and a pair of resilient fingers tangentially receivablein said recess, said fingers being yieldable radially of said shaft inresponse to axial movement thereof; and a retaining clip received insaid post slots for retaining said spring in cooperation with said onepost, said clip having at least-one bendable portion extending generallyparallel to said shaft and past said spring into engagement with one ofsaid housing shoulders at a point remote from said post slots forretaining saidclip;

ReferencesCited in the file of patent V UNITED STATES PAT ENTS 1,072,283Waters SeptfZ, 1913 1,468,275 Briggs Sept. 18, 1923 2,549,791 Fletcher-4; Apr.-24, 1951 Willyard et a1. July 20,1954

